Not killed enough undead monstrosities this Christmas? Let Valve fix that for you. Left 4 Dead 2 is now free on Steam . In case you've missed it thus far, Left 4 Dead is blooming brilliant. You and up to three human buddies fight through 90 minute missions set in different zombie-infested locales across America. The zombie throngs are managed by an AI director, which measures your health and stress levels and doles out varying degrees of punishment to match your perceived mood. Watch out, also, for the special infected - hideous supermutants with unique ways of punching/eating/melting your face.
The Left 4 Dead 1 maps have all been ported into the sequel, making Left 4 Dead 2 the definitive entry in the series. There are also plenty of fan-made campaigns and mods on the Steam workshop, including a Helm's Deep Lord of the Rings map and a mod that turns your party of survivors into Velociraptors .
According to a Left 4 Dead 2 Steam announcement , the game will be free until 10AM PST 26/12/2013. Go, go, go.